Have you been pruning this hydrangea? Most big leaf hydrangeas (grandiflora with the big balls of blooms) flower on two year old wood so pruning can snip off the buds. Also if it is in an area of cold winter winds the freezing temps can damage flower buds. No need to fertilize as too much nitrogen can produce lots of healthy leaves and no flowers. Don't prune, don't feed and see if it blooms next year. If not, use the shovel solution. Dig it out and move it to a more protected site or into the compost pile it must go. Life is too short to put up with disappointing plants. Keep growing, Marianne Binetti